Cans of this kind serve for the storage of strongly aroma containing products such as coffee, tea, tobacco or spices. With common utility cans the air space above the products contained in the can, becomes larger and larger with the sequential withdrawal of the products. Thus the air circulation in the air space above the contents caused by temperature differentials between the inner space and the environment increases significantly and thus the aroma of the contents suffers.
To solve this problem cans have been suggested which keep the air volume above the contents of the can as small as possible. U.S. Pat. No. 2,726,012 achieves this by means of a lid which contacts the contents and forms a tight seal with the inner sidewall of the can. The lid is either manually pressed onto the contents or it sinks down by gravity.
The European Patent application No. 135 974 describes a can where a clog attached to the lid which is pressed from above onto the contents of the can. The German utility model No. 72 32 726 shows a can also having a lid sitting on the contents of the can. The contents are withdrawn in the area of the bottom of the can. The lid slides down during withdrawal of the contents.
It is an object of this invention to provide a can for aroma containing materials in which the aroma also on the top layer of the contents is maintained independently of the level of filling of the can, which can also allow the convenient and easy withdrawal of the contents in the usual fashion and which can be produced for a reasonable price.
This problem is solved in accordance with this invention by a can for aroma containing products having a shiftable means for minimizing the air volume above the contents, when said shiftable means is a bottom or support element carrying the contents.
The can in accordance with this invention guarantees that the air volume above the contents can always be maintained as small as possible. Thus, a turbulance or whirling of the air and a resulting withdrawal of aroma materials is prevented.
In a preferred embodiment of this invention the bottom element of the can is height adjustable through a rotation of the lid. For achieving this, pulling means are provided which are attached to a rotatable ring, which is supported for rotation in a plane substantially orthogonal to the direction of movement of the bottom element, so that the tangential pulling force applied by the pulling means is turned into a pulling in the direction of the movement of the bottom elements by a means for changing direction.
A preferred embodiment of the can comprises at least three pulling elements having the same length and being attached to the rotatable ring in an axially offset way, wherein the azimuthal distances between the points of attachement of the pulling elements on the rotatable ring and the corresponding means for changing direction have a different size in order to compensate for the axial offset.
In a yet further preferred embodiment of this invention the bottom element is both movable upwardly by means of upper means for rotation and pulling and is movable downwardly by means of lower elements for rotation and pulling. In accordance with a still further preferred embodiment the bottom element of the can is provided with a sealing means, which are preferably directed upwardly and which contacts the inner wall of the can when subjected to a load from above.
In a still further preferred embodiment of the can, the internal diamenter of the space, for receiving the contents converges (inwardly) in its upper section or upper end, in order to bring the upper layers of the contents to the center and thus prevent a caking of the contents in the corners during the upward movement of the bottom element.
The lid of the can can be used for actuating the rotatable ring. For that purpose the lid preferably is provided with two gripping elements or connector means, which cooperate with corresponding complementary pieces in the rotatable ring and which at the same time define the regular position of the lid relative to the rotatable ring. The gripping elements or connector elements and the corresponding complementary elements can be arranged so that the rotatable ring can be rotated via the lid only in one direction. The gripping elements or connector elements can be provided with overload safety means which are activated before a rotational momentum is applied to the rotatable ring, which would place excessive strain on the pulling means.
In a still further preferred embodiment the can is provided with display means showing the level of filling of the can, these level means in particular comprise an indicator attached to the lid and a marking applied to the outside of the can. The angular and axial position of the rotatable ring can be fixed by appropriate fixing means cooperating with counterparts in the wall of the can.
In a yet further preferred embodiment the lower end or bottom end of the can comprises an air opening to facilitate the lowering of the movable bottom element, which is necessary before reloading or refilling the can.
The can in accordance with a yet further preferred embodiment of the invention is provided with guiding notches or grooves for the pulling means.
The pulling means in a preferred embodiment of the can are made out of plastic threads, which on both ends have a first area of increased cross-section and at the end of the first area of increased cross-section have a second area of increased cross-section.
The lid of the can comprises in a further preferred embodiment of the invention a plane or flate area which reaches all the way to the contents of the can. This plane or planar area preferably is either a fill element or is shaped into the lid as a cup-like recess.
The lid in accordance with a yet further preferred embodiment of the invention is provided with a ram reaching passed the outside of the can and having slots, said lid being held on the can by spring force. The lid in this embodiment can be readily turned and can be removed by simply pulling.